Keeping the Confusion Out of NPT Pipe Thread Dimensions

I recently had the pleasure of helping a caller solve a problem with a Super Air Nozzle.  He had measured the opening on the outlet of his air gun, and ordered accordingly…unfortunately, he didn’t know that 3/8 NPT did NOT correspond to a 3/8″ diameter of a threaded fitting.  I explained the reason for this, a while back, in a blog entitled “When Is A Half Inch Not A Half Inch? When It’s Half Inch Pipe, Of Course!

The ID of a 1/8 NPT threaded fitting is actually pretty close to 3/8". Here's a dimensions table that I reference often.

The ID of a 1/8 NPT threaded fitting is actually pretty close to 3/8″ (left.) Here’s a link to a dimensions table that I reference often to keep this (on right, a 3/8 NPT nozzle with an 1/8 NPT air gun) from happening.

 

As you can see, the Model 1105 3/8 NPT Super Air Nozzle will not fit the 0.405″ (not far at all from 3/8″ if measured with a ruler) ID of a 1/8 NPT threaded connection.  No matter; these are all catalog parts that we have plenty of stock on, so, after a brief discussion of pipe thread sizes, he got a Model 1103 1/8 NPT Super Air Nozzle, and it fits just fine:

IMG_5789

Model 1103 1/8 NPT (male) Super Air Nozzle installed in a 1/8″ NPT air gun.

Sometimes, an adapter is required for air guns that have straight threads.  Two common sizes for these are 5/8″-28 and 3/4″-32 – and we have adapters for both of these (call for details.) Other adapters are readily commercially available…you may find them in the plumbing aisle of your hardware store, or from a local pipe & pipe fitting supplier.  We’ve seen some air guns, though, that have a proprietary thread that doesn’t match up to anything else…in these cases, we have four types of Safety Air Guns on the shelf, ready to ship.

If you’d like to find out more about using quiet and efficient engineered Super Air Nozzles for your air gun applications, give me a call.

Russ Bowman
Application Engineer
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